Abstract: A Particle Image Velocimetry is used to display the flow field of curved inlet cut off valve in this paper.Meanwhile, the RNG k-ε turbulence model is applied to simulate the turbulent flows in the symmetrical planes of curved and inclined inlet cut off valves.The control equations are solved in a body-fitted corrdinate by finite volume method with a staggered grid system.The computed results of curved inlet cut of valve are well in agreement with the experimental data,show that of curved inlet cut-off valve.The calculat ion results also show that the RNG k-ε turbulence model can be used to simulate the separated turbulent flows with eddies.